0776 Altered Salience Network Connectivity to Sleep-Related Sound Moderates the Insomnia–Depression Association in Rotating Shift Workers

Abstract Introduction Misalignment between circadian and social rhythms in shift workers (SW) is associated with sleep and psychiatric problems. Altered brain response to sleep-related sounds (SS) may reflect increased sleep disruption. We examined neural responses to SS in SW versus healthy controls (CON)and tested whether SS-related brain activity moderates the relationship between mood symptoms, insomnia severity, and 24-hour rest-activity rhythm (RAR). Methods SW (n = 57; 75.4% female) and CON participants (n = 56; 71.4% female) completed self-report questionnaires, including the Insomnia Severity Index (ISI), Beck Depression Inventory (BDI), and Beck Anxiety Inventory. All participants underwent overnight polysomnography and a week of actigraphy accompanied by daily sleep diaries. 24-hour RAR were derived using cosinor analysis. During functional MRI, participants listened to SS and control sounds (CS). Brain activation to SS (vs. CS) were compared between groups. A moderation analysis was performed using ISI as the outcome variable and BDI, BAI, and 24-hour RAR as predictors, including brain regions showing group differences as moderators. Results SW presented higher ISI (W = 1985, p = 0.025) and BDI scores (W = 1915, p = 0.043), and lower interdaily stability, relative amplitude, and higher least active 5-hour period (all-ps < 0.001). SW had greater functional connectivity (FC) between the left anterior insula and supramarginal gyrus extending to middle frontal gyrus during sleep-related sound (vs. control sound) compared to CON (t = 4.76, p < 0.001). In addition, FC between right supramarginal gyrus (SMG) and subcallosal cortex extending to frontal medial cortex and frontal orbital cortex were lower in SW compared to CON (t = -4.96, p < 0.001). In SW, BDI score was more strongly associated with ISI when AI-SMG FC was higher than when AI-SMG FC was lower, while hearing SS (vs. CS). Conclusion Our results suggested differential brain activity to sleep-related stimuli in SW. Moreover, the findings indicate that increased right AI-SMG FC in SW can be associated with increased impact of depression on insomnia severity. Therefore, AI–SMG connectivity may represent a potential target for managing mood problems and sleep disturbances in shift workers. Support (if any) National Research Foundation (No. 2016M3C7A1904338 and No. 2022R1A2C1008209).